The present invention relates to a magnetic disk drive and, more particularly, to a magnetic head slider capable of suppressing the decrease of its flying height when used at a high altitude.
To increase recording density in recording data by a magnetic disk drive for high-density recording having a magnetic head slider (hereinafter referred to simply as “slider”) provided with a magnetic head, it is important to reduce a flying height defined by a clearance between the slider and a rotating magnetic disk. Therefore, it is important to prevent the reduction of flying height as effectively as possible when the magnetic disk drive is used at a high altitude.
Generally, the flying height of the slider decreases at a high altitude because the mean free path of air serving as a working fluid for the slider increases at a high altitude. The reduction of the flying height is undesirable from the viewpoint of the reliability of the magnetic disk drive because the reduction of the flying height increases the possibility of the slider coming into contact with the magnetic disk. It is particularly desirable for a magnetic disk drive using a 2.5 in. or smaller disk and built in a portable information processing device that is often used at a high altitude to prevent the change of the flying height of the slider with the increase of altitude, i.e., with the drop of the atmospheric pressure.
A technique for suppressing the reduction of the flying height of the slider with the increase of altitude is disclosed in JP-A No. 2000-57724 (Patent Document 1). According to Patent Document 1, the reduction of the flying height at a high altitude can be effectively suppressed by optimizing the ratio between the depth of a step bearing surface and the depth of a negative-pressure groove.
Known magnetic head sliders similar in construction to a magnetic head slider according to the present invention are disclosed in JP-A Nos. 6-203514, 8-102164, 11-25629, 2003-151233, 2001-250215 and 2000-260015, and PCT Patent Publication No. WO2003/515869. All those magnetic head sliders use a rail having a stepped surface or provided with a pad on an air inlet side to reduce adhesion and friction between the slider and the magnetic disk when the slide comes into contact with the magnetic disk.
The following patent documents are cited in the present specification:    Patent Document 1: JP-A No. 2000-57724;    Patent Document 2: PCT Patent Publication No. WO2003/515869;    Patent Document 3: JP-A No. 8-102164;    Patent Document 4: JP-A No. 11-25629;    Patent Document 5: JP-A No. 2003-151233;    Patent Document 6: JP-A No. 6-203514;    Patent Document 7: JP-A No. 2001-250215; and    Patent Document 8: JP-A No. 2000-260015.